Was the universe made for us?

today i want to talk about the claim that our universe is especially made for humans are fine-tuned for life according to this idea it's extremely unlikely our universe would just happen to be the way it is by chance and the fact that we nevertheless exist requires explanation this argument is popular among some religious people who use it to claim that our universe needs a creator and the same argument is used by physicists to pass off unscientific ideas like the multiverse or naturalness as science in this video i will explain what's wrong with this argument and why the observation that the universe is this way and not some other way is evidence neither for nor against god or the multiverse okay so here's how the argument goes in a nutshell the currently known laws of nature contain constants some of these constants are for example the fine structure constant that sets the strength of the electromagnetic force planck's constant newton's constant the cosmological constant the mass of the higgs boson and so on now you can ask what would a universe look like in which one or several of these constants were a tiny little bit different turns out that for some changes to these constants processes that are essential for life as we know it could not happen and we could not exist for example if the cosmological constant was too large then galaxies wouldn't have a form if the electromagnetic force was too strong nuclear fusion could not light up stars and so on there's a long list of calculations of this type but they're not the relevant part of the argument so i don't want to go through the whole list the relevant part of the argument goes like this it's extremely unlikely that these constants would happen to have just exactly the values that allow for our existence therefore the universe as we observe it requires an explanation and then that explanation may be god or the multiverse or whatever is your pet idea particle physicists use the same type of argument when they ask for a next larger particle collider in that case they claim it requires explanation why the mass of the higgs boson happens to be what it is this is called an argument from naturalness i explained this in an earlier video what's wrong with the argument what's wrong is the claim that the values of the constants of nature that we observe are unlikely there is no way to ever quantify this probability because we will never measure a constant of nature that has a value other than the one it does have if you want to quantify a probability you have to collect a sample of data you could do that for example if you were throwing dice throw them often enough and you get an empirically supported probability distribution but we do not have an empirically supported probability distribution for the constants of nature and why is that is because they are constant saying that the only value we have ever observed is unlikely is a scientifically meaningless statement we have no data and we will never have data which allow us to quantify the probability of something we cannot observe there's nothing quantifiably unlikely therefore there's nothing in need of explanation if you look at the published literature on the supposed fine-tuning of the constants of nature the mistake is always the same they just postulate a particular probability distribution it's this postulate that leads to that conclusion this is one of the best known logical fallacies called begging the question or circular reasoning you assume what you need to show and instead of showing that a value is unlikely they pick a specific probability distribution that makes it unlikely they could as well pick a probability distribution that would make the observed values likely just that this doesn't give the result they want to have and by the way even if you could measure a probability distribution for the constants of nature which you can't then the idea that our particular combination of constants is necessary for life would still be wrong there are several examples in the scientific literature for laws of nature with constants nothing like our own that for all we can tell allow for chemistry complex enough for life please check the info below the video for references let me be clear though that fine-tuning arguments are not always unscientific the best-known example of a good fine-tuning argument is a pen balanced on its tip if you saw that you'd be surprised because this is very unlikely to happen just by chance you'd look for an explanation a hidden mechanism that sounds very similar to the argument for fine tuning the constants of nature but the balance pan is a very different situation the claim that the balanced pen is unlikely is based on data you are surprised because you don't normally encounter pens balanced on that tip you have experience meaning you have statistics but it's completely different if you talk about changing constants that cannot be changed by any physical process not only do we not have experience with that we can never get any experience i should add there are theories in which the constants of nature are replaced with parameters that can change with time or place but that's a different story entirely and has nothing to do with the fine-tuning arguments it's an interesting idea though maybe i should talk about this some other time let me know in the comments and for the experts yes i have so far specifically referred to what's known as the frequentest interpretation of probability you can alternatively interpret the term unlikely using the bayesian interpretation of probability in the bayesian sense saying that something you observe was unlikely means you didn't expect it to happen but with the bayesian interpretation the whole argument that the universe was especially made for us doesn't work that's because in that case it's easy enough to find reasons for why your probability assessment was just wrong and nothing's in need of explaining example did you expect a year ago that we'd spent much of 2020 in lockdown probably not you probably consider that unlikely but no one would claim that you need god to explain why it seemed unlikely what does this mean for the existence of god or the multiverse both are assumptions that are unnecessary additions to our theories of nature in the first case you say the constants of nature in our universe are what we have measured and god made them in the second case you say constants of nature in our universe are what we have measured and there are infinitely many other unobservable universes with other constants of nature neither addition does anything to improve our theories of nature but this does not mean god or the multiverse do not exist it just means that evidence cannot tell us whether they do or do not exist it means god and the multiverse are not scientific ideas if you want to know more about fine-tuning i have explained all this in great detail in my book lost in math in summary was the universe made for us we have no evidence whatsoever that this is the case this video was sponsored by brilliant which is a website and app that offers interactive courses on a large variety of topics in science and mathematics the great thing about brilliant is that it allows you to build up your knowledge gradually starting from the basics up to very advanced topics and you get instant feedback on how well you are doing by answering the questions in their courses to get more background on this video's topic for example have a look at their courses on statistics and probability to support this channel and learn more about brilliant go to brilliant.org sabine and sign up for free the first 200 subscribers using this link will get 20 off their annual premium subscription thanks for watching and don't forget to subscribe if you haven't already see you next week

Channel: Sabine Hossenfelder

Views: 350,941

Keywords: is the universe made for humans, unmoved mover, universe made for life, finetuned universe, finetuning, universe made by god, multiverse, multiverse theory, was the universe made for us, was the universe made for life, universe, space, hossenfelder, cosmology, science, physics, science without the gobbledygook

Id: c6DP5lgzmTA

Length: 8min 46sec (526 seconds)

Published: Sat Jan 16 2021